Method of obtaining higher pressures with a diaphragm compressor and diaphragm compressor for carrying out said method



2 Sheets-Sheet 1 F. sTRAssBURGER CARRYING OUT SAID METHOD April 2s, 1970METHOD OF OBTAINING HIGHER PRESSURES WITH A DIAPHRAGM COMPRESSOR ANDDIAPHRAGM COMPRESSOR FOR Filed June 13, 1968 Apnl 2.8, 1970 F.srRAssBURGER 3,508,845

METHOD OF OBTAINING HIGHER PRESSURES WITH A DIAPHRAGM COMPRESSOR ANDDIAPHRAGM COMPRESSR FOR CARRYING OUT SAID METHOD Filed June 13, 1968 2Sheets-Sheet 2 United States Patent C) 3,508,845 METHOD OF OBTAININGHIGHER PRESSURES WITH A DIAPHRAGM COMPRESSOR AND DIAPHRAGM COMPRESSORFOR CARRYING OUT SAID METHOD Friedhelm Strassburger, Mulheim, Germany,asslguor to Andreas Hofer Hochdruck-Apparatebau G.m.b.H., Mulheim(Ruhr), Germany Filed June 13, 1968, Ser. No. 736,663 Claims priority,application Germany, .lune 14, 1967, H 62,999 Int. Cl. F04b 39/06,45/00; F15b 7/00 U.S. Cl. 417-32 8 Claims ABSTRACT OF THE DISCLOSURE Ahigh pressure diaphragm compressor in which the cylinder with thereciprocable actuating plunger is heated, and in which heated up oil ispumped by said plunger to the diaphragm of said diaphragm compressor.

The present invention relates to a method of obtaining higher pressureswith a diaphragm compressor and also concerns a diaphragm compressor forcarrying out said method.

Diaphragm compressors for compressing gases are employed particularly ininstances where it is important to protect the gas to be compressedagainst soiling by lubricants.

The fundamental elements of a diaphragm compressor comprise thehydraulic system and the gas section. These two parts are separated fromeach other by a suitable diaphragm. The gas part has a cover in whichthere is provided a suction and a pressure valve through which the gasflows during the compression action. The cover forms the confiningsurface of the chamber located on the gas side above the diaphragm. Atthe hydraulic side the diaphragm rests upon a plate provided with thinbores, and the bores establish connection between the chamber on thehydraulic side of the diaphragm and the chamber above the hydraulicpiston in the hydraulic cylinder. The reciprocatory movement of thehydraulic piston is transferred to the hydraulic oil and from there tothe diaphragm which now, due to its oscillating movement is adapted todraw in gas and compress the same. Diaphragm compressors of this designand operation are known.

With auxiliary compressors working with high end pressures and thus withrelatively high intake pressures, the diaphragm breaks relativelyeasily, and this failure is seen in the bores of the plate in connectionwith the very high gas intake pressures. While it is possible todimension the bores theoretically so small that the danger of breakagefor the diaphragms is eliminated to a major extent, such a design,however, has the drawback that the compression end pressure cannot beselected as high as desired. In this connection it has been found thatthe hydraulic oil at high pressure becomes rather viscous and thick.Inasmuch as this viscous mass will, in the narrow bores of the plate,produce a very high pressure head, pressure peeks occur which lead tothe destruction of the plate and of the hydraulic cylinder. The limit ofthe maximum obtainable compression end pressure is determined by thesize of the bores in the plate and, more specifically, by such freeinner diameter of the bores which offers too high a resistance againstthe viscous hydraulic oil under high pressure. On the other hand, thebores must be relatively small because otherwise the diaphragm would bedestroyed under the inuence of the high gas intake pressure.

It is an object of the present invention to provide a method and devicewhich on one hand will permit further Patented Apr. 28, 1970 to increasethe gas end pressure while on the other hand will relieve the plate andthe hydraulic cylinder from dangerous high pressure heads.

These objects and other objects and advantages of the invention willappear more clearly from the following specification, in connection Withthe accompanying drawings, in which:

FIGURE 1 is a diagrammatic illustration and shows a vertical crosssection through a diaphragm compressor with a container for thehydraulic oil and with inlet and outlet conduits.

FIGURE 2 shows an electric circuit for preventing operation of thecompressor when the temperature of the operating oil is insuicient.

The method according to the present invention is characterized primarilyin that the hydraulic cylinder and the parts adjacent thereto arepreheated and that warm oil is employed as operating uid. These stepsbring about that also at high pressures, the liquid character of the oilremains maintained and that no inadmissible or dangerous pressure headscan occur in the bores of the plate. This has the advantage that notonly will there be obtainable very high gas pressures, but also breakageof the diaphragm will for all practical purposes be excluded.

According to a preferred method of the present invention, the warm oilserving as operating liquid is also simultaneously employed for heatingthe hydraulic cylinder. This results in a simplied circuit for theliquids, and it is not necessary to keep available two diierent liquids.

A diaphragm compressor for carrying out the above mentioned method is,according to the present invention, characterized in that the hydrauliccylinder within the range of the piston has a double mantle or doublewall, the inner chamber of which through inlet and outlet conduits withinterposed circulating pump is connected to a container or tank with aheating means for hydraulic oil. The diaphragm compressor according tothe present invention is furthermore characterized in that the innerchamber of said container is through additional inlet and outletconduits by means of an interposed high pressure pump connected to theinterior of the hydraulic cylinder at the head side of the piston.

This design permits an easy heating up of the compressor body and also asimple way of placing the conduits for the operating liquid.

According to a preferred embodiment of the invention, a pressurelimiting valve may be arranged in the outlet conduit for the operatingliquid. In this way the desired pressure can be precisely maintained.

According to a further `development of the present invention, a contactthermometer may be placed in the ow path of the hydraulic oil, whichthermometer at a predetermined minimum temperature which is expedientfor obtaining the desired effect, acts upon an electric relay, which inits turn closes a contact and thereby an electric circuit for initiatingoperation of the driving motor for the diaphragm compressor. Thus, themotor is started only and remains in operation only when the hydrauliccylinder has the said minimum temperature. In this way, also during thestarting phase care will be taken that the diaphragm will not break, inview of too high pressure head in the bores of the plate below thediaphragm. Corresponding remarks also apply to the period duringoperation.

According to a still further development of the invention, in theelectric circuit for initiating operation of the driving motor thereis'provded a relay with closing contact, which relay is in series withan overload safety switch acting upon a breaker switch. This relayresponds to the actuation of a switch for starting the circulating pumpso that the motor can start and remain in operation only when thecirculating pump feeds. As a result thereof, a

second safety feature is obtained in view of which the compressor, incase of a failure of the circulating pump and the probability inherentthereto that the temperature of the hydraulic oil drops will be turnedoff automatically.

Referring now to the drawings in detail, the diaphragm compressor showntherein comprises a cover 1 arranged on the gas side and provided with asuction valve and a pressure valve for the gas to be compressed. Thecompressor furthermore comprise-s a diaphragm 2 at the bottom side ofthe cover 1, and also comprises a plate 3 with fine bores 4, said platebeing arranged on 4the bottom side of the diaphragm 2. The compressoralso includes a hydr-aulic cylinder 5 carrying the plate 3 and the cover1 and having a plunger 6 reciprocally arranged therein and surrounded bya seal 7. At a suitable place of the machine there is provided acontainer or tank -8 for the hydraulic oil which within the tank has aheating device 9, for instance, an electric resistance heater withtemperature control, for heating up the tank and the contents thereof.The hot oil is, by means of a circulating pump 10 delivered through afeeding conduit 8a into the interior chamber 5a of a double mantle ordouble walled part in the central area of the hydraulic cylinder v5where it heats up the hydraulic cylinder and the parts adjacent thereto.The oil which has given olf its heat content leaves the chamber 5athrough a discharge conduit 8b and returns to the tank 8.

A high pressure pump 11 which is driven by a motor 13 (indicated in FIG.2 only) through the intervention of a transmission of any standard type,for instance, a crank drive (not shown), delivers the hot hydraulic oilfrom the tank 8 through a feeding line 8c into the space above theplunger 6 into the hydraulic cylinder S. From here the liquid passesthrough bores 4 in plate 3 below the diaphragm 2. -In View of thispost-feeding of operating liquid through conduits 8c, also losses willbe compensated for which might have by-passed the seal 7. The hydraulicoil excessively introduced into the cylinder chamber passes through apressure limiting valve 12 or check valve and a return conduit y8d backto the oil tank 8.

The preheated machine and the preheated hydraulic oil bring about thatthe hydraulic oil will also at high pressure remain liquid and that,therefore, too high pressure heads cannot occur in the bores 4.

FIG. 2 illustrate-s an electric circuit which is adapted to excludedamages to the compressor as a result of improper operation. The circuitshows the circulating pump 10 with the driving motor 10a pertainingthereto, the driving motor 13 for the diaphragm compressor, a relay 14for turning on and turning off the compressor motor, and a relay 15 foractuating the motor of the circulating pump 10. The relay 15 comprises aclosing contact 15a which is shown in the lower part of FIG. 2. AContact thermometer 16 which is arranged at a suitable pl-ace within thecircuit of the operating liquid is connected to a relay 17 by theclosing switch 15a. Two switches 18 `and 19 and an overload safetydevice 20 on the circulating pump 10 and an opening Contact 20a completethe circuit.

The purpose of the circuit consists in permitting the star-ting of thedriving motor 13 for the diaphragm compressor only when the machine hasreached a minimum temperature which latter is measured and indicated bythe contact thermometer 16. As soon `as the minimum temperature lhasbeen obtained, the relay 17 is switched on and closes the contact 17a.The compressor could now be started through the switch 18, however, asecond safety feature is provided, namely, the relay 15 with the contactswitch 15a. This second safety feature brings about that the machine canrun only when the circulating pump 10 is in operation, in other wordsWhen the relay 15 is attracted by the switch 19. It it should occur thatthe motor of the circulating pump 10, due to an overload, is switchedoff by means of the fuse or overloading safety device 20 and the openingswitch 20a pertaining thereto, the relay 15 will open and also therel-ay 14 pertaining to the compressor motor 13 because the switch 15aopens and the driving motor 13 stops.

Thus, a turning on of the motor 13 is possible only when the minimumtemperature of the hydraulic oil or of the machine has been obtained andwhen the circulating pump is in operation. If, however, the temperatureof the oil and of the machine drops during operation below the adjustedminimum value, relay 17 becomes operative, opens switch 17a, and bringsabout that the relay 14 in view of the opening switch 17a andconsequently also the driving motor 13 for the compressor will beswitched olf.

It is, of course, to be understood that the present invention is, by nomeans, limited to the particular structural arrangement and circuitshown in the drawings, but also comprises various mod'itications withinthe scope of the invention.

What is claimed is:

1. A method of creating high pressures in a diaphragm compressor havinga hydraulic cylinder with a plunger therein at indispensable hightemperature level, which includes the steps of: preheating directly saidhydraulic cylinder and adjacent parts thereof, and feeding directlypreliminarly headed up operating oil to said plunger to be pumped by thelatter to the diaphragm of said compressor for steady heat interchangedirectly therewith` 2. A method according to claim 1, which includes thestep of: employing a portion of the preliminarily heated up oil directlyfor uniformly pre-heating said hydraulic cylinder from inside and fromoutside thereof simultaneously maintained at the same temperature byutilization of the preliminarily heated up oil directly as the same feating medium.

3. A diaphragm compressor which includes: a cylinder jacket meanssurrounding said cylinder and defining chamber means therewith, plungermeans reciprocable in said cylinder and having a pressure exerting end,pumping diaphragm means having one side thereof in fluid communicationwith said pressure exerting end and having its opposite side arrangedfor communication with a gas to be compressed, fluid reservoir means,heating means associated with said fluid reservoir means for heating uidtherein, rst conduit means including high pressure pump means forestablishing fluid communication between said reservoir means and saidpressure eX- erting end of said plunger means and conveying heated upactuating tiuid thereto, and second conduit means including fluidcirculating pump means for establishing lluid communication between saidreservoir means and said chamber means and conveying heated up uid tosaid chamber means for heating up said cylinder.

4. A compressor according to claim 3, in which said rst conduit meansincludes a return conduit communieating with said pressure exerting endand leading yback to said reservoir means, and check valve meansinterposed in said return conduit.

5. A compressor according to claim 3, which includes: electric motormeans drivingly connected to said plunger means for actuating the same,and adjustable temperature responsive second conduit means for measuringthe temperature of the uid passed therethrough to said cylinder, saidtemperature responsive means being electrically connected to said motormeans to prevent operation thereof when the temperature measured by saidtemperature responsive means is below the temperature for which saidtemperature responsive means has been set.

6. A compressor according to claim 5, which includes: electric circuitmeans comprising an exciter circuit for said motor means, relay means,and switch means controlling said exciter circuit and adapted to beclosed by said relay means in response to the energization of the latterto thereby close said exciter circuit and permit op- 5 eration of saidmotor means, said temperature responsive means including switch meansoperable to close said circuit means for energization of said relay inresponse to said temperature responsive means measuring a ternperatureat least equal to the temperature for which said temperature responsivemeans has been set.

7. A compressor according to claim 6, which includes: additional motormeans drivingly connected to said uid circulating pump means, additionalrelay means, a control switch controlling said exciter circuit andadapted to be closed by said additional relay means in response to theenergization of the lattter, and a manually operable control switchassociated with said circulating pump means for closing the circuitthereof, said manually operable control switch being located in saidcircuit means and operable when closed to energize said additional relaymeans whereby said motor means can actuate said plunger means only whenboth said circulating pump means and said high pressure pump means arein operation.

References Cited UNITED STATES PATENTS 1,769,044 7/1930 Stevens 103-442,085,286 6/1937 Abercrombie 103-44 2,092,629 9/1937 Allen 103-44 ROBERTM. WALKER, Primary Examiner U.S. Cl. X.R.

